At around the one minute mark, I was focused on the wrong tubes, but you can hear the pop and reflection of the burst in the tube next to it.
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Jolida 302BRC suddenly powered down
- Thread starter Brent13z
- Start date
Do you mean the heater element brightness of the first tube on the left, a little past halfway in the video?
Have you tried cleaning the sockets and tube pins with DeoxIT D100L? With the amp off, remove and insert the tubes several times to completely clean off oxidation and dust from the pins.
Thanks! And good luck!
From left to right, it is the second EL34 that flashes and pops. It wasn't enough for the amp to shut down, I had to. I have not cleaned the sockets though.
Clean all tube sockets. I like Deoxit D100L. Remove and insert them like 5 times each. Be careful not to break the guide or bend the pins. Take your time!
Wipe excess cleaner from the amp and tubes.
While you do this, check whether the suspect socket feels looser than the others. The socket tangs may need tightening. Do this with all the main filter caps drained and the amp off. If you don’t know how to drain the main filter caps, or feel uncomfortable working with caps that have 500VDC stored voltage, it may be best to have a tech do it.
Have you worked “under the hood” of tube amps before?
Good luck!
Just a guess but think you either have a lose pin to socket contact or a cracked solder joint between the octal socket and the board.
Do you have a really old EL34 or a dead EL34? If so cut one pin off the tube and use it to test the tightness in each octal socket receptacle (power off of course).
If all the socket pins are nice and tight, then the next thing you may want to do is remove the bottom cover and closely inspect all the solder connections for
each octal socket.
Just my guess but I would think you may have a cracked solder joint between the socket and the board.
If you use a metal (or any conducting probe), be SURE the main filter caps are drained. Some caps can hold a charge long after shutdown.
I’d measure the quiescent B+ — before tightening any sockets.
Just as another option. Orange wood fingernail sticks make good circuit probes.
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I can only conclude at this point that I gambled on a ebay seller and lost because this amp worked flawlessly for a year and a half and I put an unknown quad in and this happens. I just hope it didn't damage the amp and I can throw the old ones in.
I'll either try it today or tomorrow. My only backup is a Musical Fidelity X-CANS tube headphone amp, but I'm kinda enjoying the sound, plus I don't want to ruin a Saturday night with the knowledge that I burned my amp! I'm in Pittsburgh, BTW.Try it and post the results.
Be sure the fuse is the correct value!
Good luck!
